Hydraulic calender



March 2, 1943. G. c. MUNRO HYDRAULIC CALENDER Filed March 1, 1939 3Sheets-Sheet 1 INVENTOR fim, 3M a -2M4 'ATTORNEYS March 2, 1943. G. c.MUNRO BYDRAULIC CALENDER Filed March 1, 1959 5 Sheets-Sheet 2 INVENTOR6- ATTORNEYS March 2, 1943. G. c. MUNRO 2,312,726

HYDRAULIC CALENDER Filed March 1, 1959 s Sheets-Sheet 3 Patented ltlar.2, 1943 UNITED STATES Search Room PATENT OFFICE HYDRAULIC CALENDERApplication March 1, 1939, Serial No. 259,156

3 Claims.

This invention relates to calender devices and means for exerting,adjusting and controlling the pressure thereon. It has a particularfield of utility on paper machines and supercalenders and is especiallyuseful in connection with automatic pressure control mechanism as, andfor the purposes described in a copending application, Serial No.259,154, filed concurrently herewith by Donald B. Bradner and George C.Munro, and entitled "Paper making.

The use of fluid pressure in calender devices, though offering manyadvantages, has heretofore found little favor in the industry because ofthe numerous difliculties involved, such as the necessity for a separatepump and accumulator for each calender, and frequently for each side ofeach calender where it is desired to have different pressures on the twosides, the short life of the usual type of pumping equipment at the highpressures and severe service incident to this use, the lack of adequatecontrols, etc.

The primary object of the present invention is to provide simple,dependable and durable means for applying and for easily, accurately andcontinuously controlling the pressure, for adjusting the pressuresimultaneously on both sides of the calender, or on one sideindependently of the other. A further object is to provide means forapplying and for independently adjusting fluid pressure on the oppositesides of one calender or a plurality of calenders from a single sourceof fluid pressure whereby only one of the expensive high duty pumpingunits will be required, and the costs of installation and maintenancewill be brought within practical limits. Other objects will be apparentfrom the further description of the mechanism involved.

For the accomplishment of these objects I employ, according to thepresent invention, a novel combination of elements, a novel valvemechanism, and a novel arrangement of controls, in connection with theapplication of hydraulic pressure to one of the rolls in a singlecalender or in each of the calenders in a group.

The novel valve mechanism which forms a part of the pressure controldevices is advantageously a duplex type of valve which provides aseparate control for each side of the calender (each end of the rolls)and which can be adjusted to vary the pressure on the two sidessimultaneously or independently, as desired. The valve mechanism is soconstructed and arranged as to maintain the pressures for which it isset regardless of variations in thickness of the material passingbetween the rolls and regardless of variations in the hydraulic pressuresupply so long as the supply pressure does not fall too low. Each partof the duplex valve mechanism is further preferably arranged to give areduced and controlled pressure in the fluid supplied to the calenderwhile maintaining the higher pressure in the supply line substantiallyundiminished.

By the use and proper arrangement of this valve and other elements, ashereinafter more particularly described, I have been able to provide asystem for applying any desired pressure to each side of one or morecalenders from a single supply of fluid under high pressure underconditions which require extremely small fluid flow and so make itpossible to use a durable pump and control without unduly increasing thecost per calender.

The present invention will be better understood by reference to theaccompanying drawings, in which one embodiment thereof has beenillustrated. In the drawings;

Figure 1 is a front elevation of a supercalender equipped with myhydraulic pressure control devices, in which the fluid circulatingsystem and the pressure control valves are shown diagrammatically and toa distorted scale with parts omitted or displaced for the sake ofclarity in the drawing;

Figure 2 is a side elevation of the same calender with a part of oneframe broken away;

Figure 3 is a vertical section of the cross head and pressure cylinder,taken on line 3-3 of Figure 2;

Figure 4 is a wiring diagram showing how the pressure control valves maybe electrically adjusted;

Figure 5 is an end view of the hydraulic pressure control valvemechanism drawn to a much larger scale, showing the preferred locationof the handwheel and pressure adjusting gears, shafts, etc., and showingdiagrammatically a power drive mechanism for the adjusting devices;

Figure 6 is a side view of the valve mechanism shown in Fig. 5 withparts broken away to show the construction more clearly;

Figure '7 is a plan view, partly in section taken on line 1-1 of Figure6, of the same valve mechanism; and

Figure 8 is a fragmentary view showing a modified form of the structuresshown in the adjacent portion of Figure 7.

Referring to Figures 1, 2 and 3, a plurality of calender rolls I I,which may be of metal or alternately of metal and other suitablematerial, are

mounted in frames I3 and I4 which are rigidly held together by tie rodsl5. The frames are slotted to form guides wherein the journal boxes l8are slidably mounted. The lowest of the rolls is journaled in fixedbearings I1 and I8 and the uppermost roll H in slidable bearings i9 and20. In order to increase the calender pressure beyond the weight of therolls themselves hydraulic cylinders 2| and 22 are mounted on crossheads 23 and 24 at the top of frames I3 and I4, so that hydraulicpressure on pistons 25 and 26 may be transmitted to the journals of theuppermost roll through rods 21 and 28 and bearing blocks l9 and 20.

Fluid, advantageously oil, under pressure is admitted to cylinders 2|and 22 through conduits 3| and 32 respectively which may be providedwith strainers 33 and 34 to prevent passage of solid or abrasivematerial which might damage the pistons or cylinders. The fluid pressurein cylinders 2| and 22 is indicated on gauges 35 and 36 respectivelywhich are connected to conduits 3| and 32, advantageously throughpressure snubbers 35--A and 36--A which may be in the form of smallorifices and are adapted to prevent damage to the gauges by suddenchanges in pressure.

Any fluid which leaks past the pistons 25 and 26 is drained away throughconduits 31 and 38 which are joined together in conduit 39 which is freefrom fluid pressure. Leakage around rods 21 and 28 is prevented bysuitable seals or packing rings 40, which, being immediately below drainopenings 31 and 38, are practically free from pressure tending to causeleakage.

Fluid under pressure is supplied from any suitable source which may bean accumulator or other means for furnishing fluid at constant pressure.Particularly in cases where a number of calenders are to be served andthe amount of fluid required is subject to considerable variation, asmore or fewer calenders are used, I prefer the devices illustrated inFigure 1. As there shown, these consist of a supply tank 50 and asuitable pump which may be of a known variable delivery type, driven bya motor 52 and equipped with a known type of control for adjusting thepump discharge as required to give any pressure for which the controldevices may be set by means of hand wheel 53. A known type of pressurecontrol valve 55 may also be used. This valve may be adjusted to deliverfluid at a predetermined pressure into pressure main 56 and returnexcess fluid through pipe 5'| to reservoir 50. The valve 55 is adjustedto maintain the hydrostatic pressure in main 55 at or somewhat above themaximum pressure required in cylinders 2| and 22 in order to give themaximum pressure which should be applied to the calender, and serves tomaintain this predetermined pressure in the pipe line on both sides ofvalve 55.

Fluid which is returned from the calender pressure control devices, ashereinafter described, passes into a return main 60, which may, whennecessary, be provided with a continuously driven pump 6| to preventback pressure in the main. This pump delivers the returned fluid,advantageously through a filtering device 62, into pipe 63 which returnsthe used fluid to supply tank 50.

In order to adjust the calender pressure to the requirements of anyparticular calendering operation, the pressure in main 56 must bereduced and properly controlled before it is introduced into cylinders2| and 22 through conduits 3| and 32. For this purpose fluid passes frommain 56 through conduit 10 and branch conduits H and 12 into pressurecontrol valves 13 and 14 which are adjusted to supply predeterminedpressures into conduits 3| and 32, as hereinafter more particularlydescribed, by turning screws 15 and 16 respectively by means of thegears I1 and 18 fixed thereon. The gears 11 and 18 are driven by gears19 and 80 mounted on shaft 8| which may be turned by a hand wheel 82which may be provided with a crank handle 82-A as illustrated in Fig. 1,or by a motor as hereinafter described. Gear I8 is turned by gear 80through an intermediate gear 84 mounted on a stub shaft 83 (see alsoFigures 5, 6 and 7) supported in a bearing 85 on the body of valve 13.By turning shaft 8| by means of hand wheel 82 (or a motor I50 ashereinafter described) the valves 13 and 14 are simultaneously adjustedto effect a simultaneous adjustment of the pressures in cylinders 2| and22.

In some cases it may be desirable to have greater pressure on one end ofthe calender rolls than on the other. If this is desired the structuremay be arranged as illustrated in Figure '7 so that by pressing inwardon hand wheel 82 gear 19 is displaced along shaft 8|, compressing spring81, and thrown out of mesh with gear ll. Shaft 8| may then be turned andwill through gears 80, 84 and 18 turn screw 16 which serves to adjustvalve 14 without changing the adjustment of valve 13, thereby securingan independent adjustment of the pressures on the two sides of thecalender, when this is required. If independent adjustment is notdesired gear 19 may be fixed instead of slidable on shaft 8|.

Screws I5 and 16 are threaded into adjusting nuts 9| and 92 respectivelywhich are prevented from turning by feet 95 and 96 respectively whichslide on the surface of the bodies of valves 14 and 13. Properlycalibrated tension springs 93 and 94 are attached to adjusting nuts 9|and 92, as shown in Figures 6 and '7 so that turning screws 15 or 16 inone direction increases and in the other direction decreases the tensionon the corresponding spring. Springs 93 and 94 are attached at theiropposite ends by clevises 91 and 98 to levers 0| and I02, which arepivoted at I03 and 14 to the respective valve bodies.

The construction of the valves and the manner in which they function tomaintain a predetermined hydrostatic pressure will be best understood byreference to Figure '7, in which valve 14 is shown in section, it beingunderstood that valve 13 is of similar construction. The valves are ofthe piston type in which piston III is accurately fitted into a smoothbore in valve body 14. Piston I is provided with a portion 2 of reduceddiameter from which a hole I I3 communicates with a central bore 4.Conduit 32 which transmits hydrostatic pressure to cylinder 22 opensinto the bore in valve 14 at a point which is always in communicationwith the space surrounding the smaller diameter portion 2 of piston I.It is thus apparent that the hydrostatic pressure ln space 5 at the endof piston III will always be the same as that in cylinder 22 whichapplies pressure to the corresponding side of the calender.

The pressure of the fluid in space 5 on the one end of piston I is thusopposed to the pressure applied to the other end of piston by spring 94acting through lever I02. As long as these pressures are equal, pistonIII will rethe piston reaches the limit of its movement.

Movement in this direction brings the reduced diameter 2 opposite, theopening of high pressure conduit 12 from pressure main 55 and permitshigh pressure fluid to'passthrough the valve into conduit 52 and thenceto cylinder 22. When the pressure in cylinder 22 and space 5 reaches therequired value, piston III is moved back by this pressure to theposition shown in Figure 'l and prevents further increase in pressure incylinder 22.

If, on the other hand, the fluid pressure exceeds the spring pressure,piston III will be moved to the left in Figure 7 thus bringing reduceddiameter II2 opposite the opening leading into exhaust conduit I20, topermit escape of fluid from cylinder 22 and conduit 92 through the valveinto exhaust conduit I20 which leads through conduit I22 into returnmain 60 and back into supply tank 50. When the pressure in cylinder 22and space II5 hasdecreased to the required amount, spring 94 actingthrough lever I02 moves piston III back to the position shown in Figure7 to prevent further decrease in pressure in cylinder 22. g

It may be noted that the movement of pistons 25 and 26 in cylinders 2|and 22 is very small, being equal only to the'small thickness of thepaper threadedbetween the rolls, and the slight compression of thenon-metallic rolls, when used, under the applied pressure. Consequentlyonly a small amount of fluid need pass through valves 15 and 14 to causeeven the maximum required change in pressure, which therefore takesplace with corresponding rapidity.

Any fluid whichmay tend to escape aroundpiston III in spite of itsaccurate fit in the bore of valve body 14 will be caught in annulargroove :25 which opens into drain conduit I26 which is free fromhydrostatic pressure and which in turn leads through conduit I22 andreturn main 60 to reservoir 50 or may, if desired, return through aseparate drain line to the reservoir in order to avoid any pressurewhich might exist in exhaust lines I20 and I22. An oil seal or packingrin'g I28 is also provided to prevent escape of oil during movement ofpiston III.

In the operation of calenders it is frequently desirable to quicklyrelease the pressure without disturbing the adjustment. To accomplish aquick release and reapplication of pressure, a handle I5l is provided.This is adapted to rock on shaft I32 from the on" position illustratedin solid lines to the"ofi position indicated by broken lines in Figure6. Rigidly attached to handle I3I are cams I33 and I34 which when thehandle is rocked to the off" position serve to rock levers I35 and I36on their pivots I31 and I50 and thereby to press plungers MI and I42respectively, as shown in Fig. 6, or to press these plungers directly ina manner which will be evident by reference to Fig. 1. As will beapparent from Figure 7, this movement of plunger I42 moves piston II Ito the left, bringing reduced diameter II2 opposite exhaust opening I20thereby releasing the pressure in cylinder 22. This will rock lever I02and extend spring 94, but will not alter the setting of adjusting nut 92which controls the pressure which will be maintained in cylinder 22 whenhandle Ill is returned to the "on" position. Plunger I4I operates in thesame manner to open valve 15 and release the pressure in cylinder 2|.Leakage around plungers HI and I42 is prevented by suitable packingglands I45 and I44.

Operation of the valve mechanism by a reversible electric motor I may insome cases be preferable to manual operation by hand wheel 62 and crank62-A as indicated in Figure l.

The motor I50 is advantageously connected through a suitable speedreduction unit I49 to a gear I49 which is arranged to drivejgear 11, andwill then operate to simultaneously adjust the tension on springs 95 and94. Depression of hand wheel 92 disengages gear 19 from gear 11 andpermits the motor to rotate screw 15 to adjust spring 95 while gear 19,shaft II; gears 80, 04, and 16, and screw 16 remain stationary and theadjustment of spring 94 consequently remains unchanged.

Operation of motor I50 to adjust the pressure control valves may becontrolled as illustrated in Figure 4. Power is advantageously suppliedfrom a three phase line a; h. 9., while the operation of the motor andits direction of rotation is controlled by switches I5I and I52 whichare closed by energizing coils I and I54 respectively. An interlockillustrated diagrammatically at I55 prevents either switch from beingclosed unless the other is open. The motor is operated in a direction toincrease the tension on springs 95 and 94 and consequently the pressureincylinders 2I and 22 by means of push button "I which closes a circuitenergizing coil I55 thereby closing switch I5l. The motor is operated inthe other direction to decrease the tension on springs 95 and 94 and thepressure in cylinders 2| and 22 by means of push button I54 which closesa circuit energizing coil I54 thereby closing switch I52. The switchesI5I and I52 are normally open switches of convention type held open,when coils I55 and I54 are not energized, by any suitable means such assprings I51 and I56 connected to a common anchorage I59, so that theyremain closed and cause the motor to operate only so long as theappropriate push button is depressed. Release of the push buttonimmediately stops operation of the motor and further change in theadjustment.

It is apparent that the adjusting mechanism would be damaged byadjustment too far in either direction. When the adjustment is mademanually by turning hand wheel 62 there is little danger of damage dueto over adjustment but in the case of electrical. adjustment, I preferto positively prevent over adjustment by the provision of limit switchesI55, I66, I61 and Ill. These switches are normally closed, but areopened by contact with the feet 95 and on adjusting nuts 9| and 92 whenthese reach the high or low limits of their respective adjustments (seealso Figure 7). Thus when either spring adjusting nut 9| or 92 reachesthe low limit of its adjustment the corresponding low limit switch I65or I65 is opened, breaking the circuit through cell I54, and openingswitch I52, thus preventing further adjustment in this direction. or 92reaches the upper limit of its adjustment the corresponding high limitswitch I61 or I55 is opened breaking the circuit through coil I55, andopening switch I'5I thus preventing further adjustment in thisdirection.

In case it should for any reason be desired to Similarly when eitheradjusting nut 9| screwed a duplicate gear I11. 19 on shaft 8| a widefaced gear I19 is substiprevent changes in the pressure adjustment whilethe pressure is turned of! and gauges 35 and 88 are at zero and will notindicate the changes, a similar switch I10 may be provided to holdcircuits through coils I53 and I54 open while handle I II is in the offposition. Switch I10 may be connected for operation by handle I3I in anysuitable manner.

' In the case of supercalenders, some of the rolls are non-metallic andmay be damaged by too great a difierence in pressure from one end of theroll to the other. Thus in these cases, though a diiference in pressuremay be necessary to secure proper calendaring action, it may bedeslrable to prevent the pressure difference from exceedingpredetermined limits. While this may be accomplished by relief valvesset to operate at the desired maximum pressure differential and insertedbetween conduits 3| and 32, I prefer a positive mechanical interlock onthe adjusting means, as illustrated in Figure 8.

For this purpose gear 11 on screw 15 may be provided with a threaded hubI18 on which is In place of gear tuted. When gear I19 is pressed inwardby hand wheel 82 against spring 81 it is disengaged from gear 11, butremains in mesh with gear I11. Then as gear 11 is rotated by the motorI50, gear I19 remains stationary and holds gear I11 against rotation sothat the rotation of gear 11 with its threaded hub I16 causes gear I11to move along the hub towards or away from gear 11 which limits itsmotion in one direction, while a collar I18, which may be adjustable ifdesired, limits its movement in the other direction. To prevent awedging action of the screw, positive stops I80, I8I and I82 may beprovided respectively on gears 11, I11 and collar I18, so that when gearI11 has been moved to the limit in either direction and the engagementof the stops I8I with stops I80 or I82 prevents further turning, ofthreaded hub I16 in gear I11, the teeth of gears 11 and I11 will be inalignment and stops I8I will drive gear I11 along with gear 11 causinggear I19 to rotate the same as if it were in mesh with gear 11. Sincewhen the stops are in contact, the teeth on gears 11 and I11 are inalignment, spring 81 can readily return gear I19 into mesh with gear 11when pressure on hand wheel 82 is released. It-may thus be seen that theamount of movement from its normal position allowed to gear I11, beforeit contacts gears 11 or collar I18, determines the limits of differencebetween the pressure adjustments of the two valves, and consequently themaximum pressure differential from one side of .the calender to theother.

When the invention is applied to a plurality or system of caienders,each of the several valve mechanisms may be individually adjusted tosupply and vary the pressure applied to the corresponding calender andto regulate the relative pressures applied to the two sides of suchcalender, all without affecting the pressure on any other calender inthe connected group. The valve mechanisms quickly and accurately providepressure changes of small or large magnitude in response to changes inadjustment and in calender pressure, and the volume of fluid flowincident to such pressure changes is very small.

The mechanism as herein described makes possible for the first time acalender system in which fluid pressure can be supplied with littlefluid flowto one or a group of calenders from a single high pressuresource of supply, and in which the valve pressures on one or both sidesof any calender can be varied at the will of the operator, by small orlarge increments, without affecting the pressure on any other calendersin the group or on the other side of the same calender.

I claim:

1. In combination, a calender comprising a plurality of rolls, a sourceof fluid under pressure not less than a predetermined minimum, means forpressing one roll in said calender against another roll thereincomprising a pressure cylinder at each end of said roll for receivingfluid under pressure and applying mechanical pressure to thecorresponding end of said roll and a conduit for each of said cylindersfor connecting said cylinder to said source of fluid under pressure,means for maintaining the pressure between said rolls at a predeterminedvalue comprising a valve in each of said conduits, each of said valveshaving associated therewith means for exerting a mechanical force, andincluding balancing means for comparing the fluid pressure in theconnected cylinder with said mechanical force, said balancing meansrespondingto conditions of unbalance by movement which admits fluid tosaid cylinder when the pressure in the cylinder is less than thatcorresponding to said force and releases fluid from said cylinder whensaid pressure exceeds that corresponding to said force, means foradjusting the pressure between the rolls in said calender comprisingmeans for simultaneously adjusting by substantially equal amounts themechanical forces with which the fluid pressures in the cylinders arecompared, and means for quickly removing pressure from the calender rollwhile maintaining the pressure adjustment undisturbed comprising amovable part for simultaneously mechanically moving both of saidbalancing means in opposition to the forces exerted by said mechani--cal force exerting means to release fluid from said pressure cylinders.

2. In apparatus of the character described, in combination, a calendercomprising a plurality of rolls, a source of fluid under pressure notless than a predetermined minimum, means for applying pressure at eachend of a roll in said calender including a hydraulic pressure cylinderassociated with each end of said roll, a conduit connecting each of saidcylinders with said source of fluid under pressure, means for separatelycontrolling the pressure at each end of said roll comprising a valvehousing in each of said conduits having an adjustable spring associatedtherewith and containing a movable piston balanced between the forceexerted thereon .by the fluid pressure in the associated cylinder and amechanical force exerted thereon by said spring, said piston acting whensaid forces are in balance to prevent pressure fluid from entering orleaving the associated pressure cylinder and when said forces are out ofbalance to admit pressure fluid to said cylinder if the force exerted bysaid spring overbalances that exerted by the fluid and to permit escapeof pressure fluid from said cylinder if the force exerted by said springis overbalanced by that exerted by the fluid, separate means foradjusting the pressure maintained by said control means at'the oppositeends of said roll, each of said adjusting means comprising screw meansfor adjusting the force exerted by said spring on the correspondingpiston, and means for providing either independeat or simultaneous andsubstantially equal adjustment of the pressure exerted at opposite endsoi the roll comprising a separable driving connection between said screwmeans whereby operation of one may also operate the other.

3. In apparatus of the character described, in combination, a calendercomprising a plurality of rolls, a source of fluid under pressure notless than a predetermined minimum, means for applying pressure at eachend of a roll in said caiender including a hydraulic pressure cylinderassociated with each end of said roll,- a conduit connecting each ofsaid cylinders with said source of fluid under pressure, means forseparately controlling the pressure at each end of said roll comprisinga valve housing in each of said conduits having an adjustable springassociated therewith and containing a movable piston balanced betweenthe force exerted thereon by the fluid pressure in the associatedcylinder' and a mechanical force exerted thereon by said spring, saidpiston acting when said forces are in balance to prevent pressure fluidfrom entering or leaving the associated pressure cylinder and when saidforces are out of balance to admit pressure fluid to said cylinder ii'the force exerted by said spring overbalances that exerted by the fluidand to permit escape of pressure fluid from said cylinder if the forceexerted by said spring is overbalanced by that exerted by the fluid,separate means for adjusting the pressure maintained by said controlmeans at the opposite ends of said roll, each of said adjusting meanscomprising screw means for adjusting the force exerted by said spring onthe corresponding piston, mean for providing either independent orsimultaneous and substantially equal adjustment of the pressures exertedon opposite ends of said roll comprising a separable driving connectionbetween said screw means whereby operation of one may also operate theother, and means for preventing the pressure at one end of said rollfrom being adjusted to dif- 'Ier by more than a predetermined amountfrom that at the other end thereof comprising means for re-establishingsaid driving connection when one of said screw means has been adjustedto cause the force exerted by one of said springs to differ by more thana predetermined amount from that exerted by the other spring.

GEORGE C. MUNRO.

